This invention relates to activated alumina and more particularly, it relates to alumina or alumina bodies containing alkali metal compounds such as sodium compounds suitable for use as an adsorbent, for example.
In forming bodies of alumina suitable for adsorbing HCl, H.sub.2 O, CO.sub.2 or H.sub.2 S, for example, the bodies can be formed by several methods. For example, alumina powder can be mixed with water to make paste which is extruded to form pellets. Or, a rotating pan may be used where dry active alumina powder is added to the pan and an aqueous solution sprayed on the powder as the pan rotates. The rotating pan forms the powder and solution into spheres. In another method, spheres can be made from a viscous slurry of the activated alumina and aqueous solution using the so-called "oil drop" method.
U.S. Pat. No. 4,273,735 discloses forming spheroidal alumina shaped articles by dispersing an ungelled admixture of an alumina sol and hexamethylenetetramaine, in the form of droplets, into a liquid forming medium which is very slightly miscible with water, the medium being at a temperature of between about 50.degree. and 105.degree. C.; next the alumina spheres are aged at a temperature greater than about 105.degree. C. at superatmospheric pressure, then the alumina spheres are aged in a basic medium, before washing, drying and calcining. The resultant shaped articles are useful as catalysts or catalyst carriers/supports.
U.S. Pat. No. 5,238,611 discloses a process for producing granulated particles from a powder which is insoluble in water. The formed granulated particles are substantially larger than those of the powder grains. The powder is mixed with an aqueous solution of a cellulose chosen from among methyl cellulose, hydroxypropyl methyl cellulose, etheric hydroxybutyl methyl cellulose. Then droplets of this mixture are made to fall into an aqueous solution of at least one metallic salt or metallic hydroxide which does not react with the particles.
U.S. Pat. No. 4,999,323 discloses production of ceramic powders by emulsion precipitation including contacting the emulsion with a gaseous reactant for the cation or cations that will react with the cation or cations to form a precipitate without breaking the emulsion. The gaseous reactant may be ammonia, which may be contacted with the emulsion until it reaches a pH of about 10 to 11.
U.S. Pat. No. 5,032,555 discloses a process for making zirconia-toughened alumina (ZTA) from precursor salts. The precursor salts are coprecipitated from solution to yield a gel in a liquid phase. The gel in excess of the critical temperature and pressure is dried at a temperature and pressure in excess of the critical temperature and pressure of the liquid phase to thereby convert the liquid phase to a gas. The solid particles, when separated from the gas, form a fine particulate ZTA which, upon consolidation yields near theoretical density toughened ceramics.
U.S. Pat. No. 4,166,100 discloses a method of preparing granulated activated alumina comprising decomposition of alumina trihydrate by heating, mixing of the obtained product of decomposition with water, its hydration, granulation, drying at a temperature of 20.degree.-150.degree. C., and calcining at a temperature of 400.degree.-600.degree. C., in which, according to the invention alumina trihydrate is decomposed by bringing it in contact with a bed of a solid heat carrier having the temperature of 350.degree.-600.degree. C., for a period of time from 0.05 to 0.5 second, to obtain an amorphous aluminum hydroxide, which is mixed with water into a suspension having the concentration of 100-500 g/liter (as Al.sub.2 O.sub.3), with subsequent hydration of this product of decomposition at a temperature of 20.degree.-100.degree. C. and the pH of 5-12 for 0.5-10 hours; before granulation of the hydrated product of decomposition, it is treated with an acid, that can form water-soluble basic salts of aluminum, at a temperature of 20.degree.-150.degree. C.
U.S. Pat. No. 5,316,998 discloses an HCl adsorbent, and method of making and using the adsorbent, the adsorbent comprising an activated alumina promoted with an alkali metal oxide. The adsorbent contains at least about 5% alkali metal oxide. This patent discloses adding the alkali metal oxide using an alkali metal salt of an organic compound that decomposes at temperatures below 500.degree. C. and liberates the organic portion.
U.S. Pat. No. 3,222,129 discloses partially dehydrated material ground so that the particles are extremely small, e.g., on the order of one to two microns. The ground particles are mixed with water to form agglomerated nodules and heated to low temperatures, e.g., about 100.degree. C., for a period of several hours to cure the nodules. The cured material is activated by heating to a temperature in excess of 700.degree. F. for a period of time.
U.S. Pat. No. 5,288,849 discloses alumina-based adsorbents containing at least one compound of an alkali or alkaline earth metal, wherein the alkali or alkaline earth metal values are present in an amount ranging from 15 mmole to 100 mmole per 100 g of alumina, are useful for the adsorptive purification of polyolefins prepared by the polymerization of olefins in the presence of a metallic coordination catalyst, to remove contaminating catalyst metal values therefrom with but negligible monomer/solvent isomerization.
British Patent 2,267,096 discloses a solid particulate absorbent material for removing acidic contaminants from hydrocarbons comprising sodium hydroxide and/or potassium hydroxide, alumina and/or zinc oxide, lime, and optionally, copper II oxide. A hydrocarbon containing an acidic contaminant is purified by passing the hydrocarbon through a bed of the particulate absorbent material.
U.S. Reissue Pat. No. 30,569 discloses that hard, rounded aggregates are produced by preparing droplets of a slurry consisting of suspending liquid containing distinct particles of a solid and dropping the droplets of the slurry onto a bed of particles under conditions where the suspending liquid of the slurry droplet is removed. This technique is especially desirable for making unique fixed-bed catalysts.
Canadian Patent 811,641 discloses forming refractory spheres by dripping a resinous mixture into an alkaline solution. Other powder-related patents include U.S. Pat. Nos. 5,266,243; 5,340,781; 4,952,144; 3,495,954 and Japanese Patent 54011-076. However, there is still a great need for improved alumina bodies having alkali or alkaline earth metal compounds incorporated therein and an improved process for providing the same.